It's not due to be published until 2013, but young adult fantasy author Garth Nix read an extract from his upcoming novel Clariel: The Lost Abhorsen, at the Edinburgh International Book Festival.

Still in draft form, Clariel is a prequel to previous Old Kingdom novels, such as Sabriel and Abhorsen. It will focus on the early life of Chlorr of the Mask, an evil necromancer and one of the Greater Dead in the fictional universe.

Nix also read from his most recent novel, Confusion of Princes, which is partly dedicated to classic science fiction writers Robert A Heinlein and Andre Norton. In writing the book, Nix said he wanted to write an old-fashioned adventure story with a modern sensibility. "I was trying to emulate the books I read growing up," he said.

In addition he revealed the first story he wrote – as a six-year-old boy. Called The Coin Shower, it was composed of just three sentences and Nix told the crowd that the three sentence story was a good exercise in structure for aspiring writers. He advised "everyone writes in different ways. There is no one true path."

In the past, Nix has worked in PR and been a reserve in the Australian army. However, since the publication of his first book, The Ragwitch, 21 years ago, he's written several science fiction and fantasy works. Demonstrating the extent of his bibliography, Nix unfolded a flip chart of his book covers, which stretched for metres across the length of the stage.

"A lot of writers give up early on," he said, gesturing to the display. "But this demonstrates what can happen if you're too dumb to quit."

Asked about the possibility of film adaptations of his books, Nix said he visited Los Angeles every year but was yet to have a successful offer from Hollywood, though negotiations over Sabriel were ongoing. "I make it more difficult by wanting to be involved," he admitted.

Nix also confirmed that Garth Nix is indeed his real name, even though many authors disbelieve him. "It's like Obama," he joked, "I have to carry my birth certificate."